This is a duplicate request and was rejected. For reasons why this occurred, and help fixing this, see http://sellercentral.amazon.co.uk/gp/help/25361
This error occurs when you appear to be submitting shipping confirmation or order fulfillment data that was previously submitted without errors. Generally, this occurs when you correct errors in a shipping confirmation file or order fulfillment feed and resubmit the data without removing the data for shipments that were successfully confirmed.
You should not confirm shipment of the same items multiple times. Amazon considers all shipping confirmation or fulfillment data to be in addition to data previously provided. If your shipping confirmation file or order fulfillment feed contained errors, first remove the data for any records that did not contain errors before submitting your modified data a second time.
To resolve this error, please remove data for shipments that were successfully confirmed before attempting additional submissions.